1. Field of the Invention
The invention relates to a connection unit.
2. Description of the Invention
Connection units are known which electrically connect a power unit such as a motor to a power-supply circuit which supplies electricity to the power unit. For assembling the connection unit, for example, a terminal of a cable connected to the power-supply circuit and a busbar connected to the power unit are sandwiched between a bolt and a nut and are tightened up to electrically connect the power-supply circuit and the power unit to each other.
JP2011-108411A discloses a terminal block (a connection unit) in which nuts are accommodated in nut-accommodating recesses formed in a terminal block housing, and in which busbars are attached in such a way as to cover the nuts. For mounting the busbars onto the terminal block housing, first, the nuts are accommodated into the nut-accommodating recesses, and then, each busbar is slid along its corresponding rib-shaped guide walls spaced apart from each other by a distance substantially equal to the width of the busbar, to bring the busbars into a temporally locked state. In the temporally locked state, movement of the busbar is restricted by: the guide walls of the terminal block housing; busbar pressers; and locks.
Next, round terminals connected to a refrigerator and the like are laid over the busbars, then bolts are inserted through holes formed in the round terminals and the busbars, and then are threaded into the nuts accommodated in the nut-accommodating recesses, whereby the busbars are held in a final locked state.
A mounting portion projects from a rear surface of the above-mentioned terminal block housing opposite to a front surface thereof in which the nut-accommodating recesses are formed. For installing the terminal block into a device, bolts are inserted into mounting holes formed through the mounting portion to fasten the terminal block to the device by the bolts.
For driving a power unit such as a motor, oil may be supplied to the power unit for maintaining the power unit at proper temperatures or reducing gear friction. In that case, the oil is circulated within the transmission case (the housing) that accommodates the power unit therein, and thus supplied to the power unit (by being ejected in a mist form, dripped, etc.).
For installing the terminal block of JP2011-108411A, bolts are inserted into holes formed in the transmission case while the mounting portion of the terminal block is contacted with the transmission case, followed by fastening the terminal block to the transmission case by the bolts.
In the terminal block, the guide walls and the busbar pressers for restricting movement of the busbars are formed in such a way that predetermined margins (clearances) are allowed relative to the dimensions of the busbars, which leads to a risk of leakage of the oil from the transmission case through the clearances formed between the terminal block housing and the busbars during the drive of the power unit. There has been a demand, therefore, of preventing the oil from leaking to the outside from the terminal block fitted on the housing such as the transmission case.
It is an aspect of an objective of the present invention to provide a connection unit that can accommodate nuts inside it and that also shows high sealing ability in a state installed on a housing.